/*
 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package java.lang.invoke;

import sun.invoke.util.BytecodeDescriptor;
import sun.invoke.util.VerifyAccess;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Member;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandleStatics.*;

import java.util.Objects;

/**
 * A {@code MemberName} is a compact symbolic datum which fully characterizes
 * a method or field reference.
 * A member name refers to a field, method, constructor, or member type.
 * Every member name has a simple name (a string) and a type (either a Class or MethodType).
 * A member name may also have a non-null declaring class, or it may be simply
 * a naked name/type pair.
 * A member name may also have non-zero modifier flags.
 * Finally, a member name may be either resolved or unresolved.
 * If it is resolved, the existence of the named
 * <p>
 * Whether resolved or not, a member name provides no access rights or
 * invocation capability to its possessor.  It is merely a compact
 * representation of all symbolic information necessary to link to
 * and properly use the named member.
 * <p>
 * When resolved, a member name's internal implementation may include references to JVM metadata.
 * This representation is stateless and only decriptive.
 * It provides no private information and no capability to use the member.
 * <p>
 * By contrast, a {@linkplain java.lang.reflect.Method} contains fuller information
 * about the internals of a method (except its bytecodes) and also
 * allows invocation.  A MemberName is much lighter than a Method,
 * since it contains about 7 fields to the 16 of Method (plus its sub-arrays),
 * and those seven fields omit much of the information in Method.
 *
 * @author jrose
 */
/*non-public*/ final class MemberName implements Member, Cloneable {

  private Class<?> clazz;       // class in which the method is defined
  private String name;        // may be null if not yet materialized
  private Object type;        // may be null if not yet materialized
  private int flags;       // modifier bits; see reflect.Modifier
  //@Injected JVM_Method* vmtarget;
  //@Injected int         vmindex;
  private Object resolution;  // if null, this guy is resolved

  /**
   * Return the declaring class of this member.
   * In the case of a bare name and type, the declaring class will be null.
   */
  public Class<?> getDeclaringClass() {
    return clazz;
  }

  /**
   * Utility method producing the class loader of the declaring class.
   */
  public ClassLoader getClassLoader() {
    return clazz.getClassLoader();
  }

  /**
   * Return the simple name of this member.
   * For a type, it is the same as {@link Class#getSimpleName}.
   * For a method or field, it is the simple name of the member.
   * For a constructor, it is always {@code "&lt;init&gt;"}.
   */
  public String getName() {
    if (name == null) {
      expandFromVM();
      if (name == null) {
        return null;
      }
    }
    return name;
  }

  public MethodType getMethodOrFieldType() {
    if (isInvocable()) {
      return getMethodType();
    }
    if (isGetter()) {
      return MethodType.methodType(getFieldType());
    }
    if (isSetter()) {
      return MethodType.methodType(void.class, getFieldType());
    }
    throw new InternalError("not a method or field: " + this);
  }

  /**
   * Return the declared type of this member, which
   * must be a method or constructor.
   */
  public MethodType getMethodType() {
    if (type == null) {
      expandFromVM();
      if (type == null) {
        return null;
      }
    }
    if (!isInvocable()) {
      throw newIllegalArgumentException("not invocable, no method type");
    }

    {
      // Get a snapshot of type which doesn't get changed by racing threads.
      final Object type = this.type;
      if (type instanceof MethodType) {
        return (MethodType) type;
      }
    }

    // type is not a MethodType yet.  Convert it thread-safely.
    synchronized (this) {
      if (type instanceof String) {
        String sig = (String) type;
        MethodType res = MethodType.fromMethodDescriptorString(sig, getClassLoader());
        type = res;
      } else if (type instanceof Object[]) {
        Object[] typeInfo = (Object[]) type;
        Class<?>[] ptypes = (Class<?>[]) typeInfo[1];
        Class<?> rtype = (Class<?>) typeInfo[0];
        MethodType res = MethodType.methodType(rtype, ptypes);
        type = res;
      }
      // Make sure type is a MethodType for racing threads.
      assert type instanceof MethodType : "bad method type " + type;
    }
    return (MethodType) type;
  }

  /**
   * Return the actual type under which this method or constructor must be invoked.
   * For non-static methods or constructors, this is the type with a leading parameter,
   * a reference to declaring class.  For static methods, it is the same as the declared type.
   */
  public MethodType getInvocationType() {
    MethodType itype = getMethodOrFieldType();
    if (isConstructor() && getReferenceKind() == REF_newInvokeSpecial) {
      return itype.changeReturnType(clazz);
    }
    if (!isStatic()) {
      return itype.insertParameterTypes(0, clazz);
    }
    return itype;
  }

  /**
   * Utility method producing the parameter types of the method type.
   */
  public Class<?>[] getParameterTypes() {
    return getMethodType().parameterArray();
  }

  /**
   * Utility method producing the return type of the method type.
   */
  public Class<?> getReturnType() {
    return getMethodType().returnType();
  }

  /**
   * Return the declared type of this member, which
   * must be a field or type.
   * If it is a type member, that type itself is returned.
   */
  public Class<?> getFieldType() {
    if (type == null) {
      expandFromVM();
      if (type == null) {
        return null;
      }
    }
    if (isInvocable()) {
      throw newIllegalArgumentException("not a field or nested class, no simple type");
    }

    {
      // Get a snapshot of type which doesn't get changed by racing threads.
      final Object type = this.type;
      if (type instanceof Class<?>) {
        return (Class<?>) type;
      }
    }

    // type is not a Class yet.  Convert it thread-safely.
    synchronized (this) {
      if (type instanceof String) {
        String sig = (String) type;
        MethodType mtype = MethodType.fromMethodDescriptorString("()" + sig, getClassLoader());
        Class<?> res = mtype.returnType();
        type = res;
      }
      // Make sure type is a Class for racing threads.
      assert type instanceof Class<?> : "bad field type " + type;
    }
    return (Class<?>) type;
  }

  /**
   * Utility method to produce either the method type or field type of this member.
   */
  public Object getType() {
    return (isInvocable() ? getMethodType() : getFieldType());
  }

  /**
   * Utility method to produce the signature of this member,
   * used within the class file format to describe its type.
   */
  public String getSignature() {
    if (type == null) {
      expandFromVM();
      if (type == null) {
        return null;
      }
    }
    if (isInvocable()) {
      return BytecodeDescriptor.unparse(getMethodType());
    } else {
      return BytecodeDescriptor.unparse(getFieldType());
    }
  }

  /**
   * Return the modifier flags of this member.
   *
   * @see java.lang.reflect.Modifier
   */
  public int getModifiers() {
    return (flags & RECOGNIZED_MODIFIERS);
  }

  /**
   * Return the reference kind of this member, or zero if none.
   */
  public byte getReferenceKind() {
    return (byte) ((flags >>> MN_REFERENCE_KIND_SHIFT) & MN_REFERENCE_KIND_MASK);
  }

  private boolean referenceKindIsConsistent() {
    byte refKind = getReferenceKind();
    if (refKind == REF_NONE) {
      return isType();
    }
    if (isField()) {
      assert (staticIsConsistent());
      assert (MethodHandleNatives.refKindIsField(refKind));
    } else if (isConstructor()) {
      assert (refKind == REF_newInvokeSpecial || refKind == REF_invokeSpecial);
    } else if (isMethod()) {
      assert (staticIsConsistent());
      assert (MethodHandleNatives.refKindIsMethod(refKind));
      if (clazz.isInterface()) {
        assert (refKind == REF_invokeInterface ||
            refKind == REF_invokeStatic ||
            refKind == REF_invokeSpecial ||
            refKind == REF_invokeVirtual && isObjectPublicMethod());
      }
    } else {
      assert (false);
    }
    return true;
  }

  private boolean isObjectPublicMethod() {
    if (clazz == Object.class) {
      return true;
    }
    MethodType mtype = getMethodType();
    if (name.equals("toString") && mtype.returnType() == String.class
        && mtype.parameterCount() == 0) {
      return true;
    }
    if (name.equals("hashCode") && mtype.returnType() == int.class && mtype.parameterCount() == 0) {
      return true;
    }
    if (name.equals("equals") && mtype.returnType() == boolean.class && mtype.parameterCount() == 1
        && mtype.parameterType(0) == Object.class) {
      return true;
    }
    return false;
  }

  /*non-public*/ boolean referenceKindIsConsistentWith(int originalRefKind) {
    int refKind = getReferenceKind();
    if (refKind == originalRefKind) {
      return true;
    }
    switch (originalRefKind) {
      case REF_invokeInterface:
        // Looking up an interface method, can get (e.g.) Object.hashCode
        assert (refKind == REF_invokeVirtual ||
            refKind == REF_invokeSpecial) : this;
        return true;
      case REF_invokeVirtual:
      case REF_newInvokeSpecial:
        // Looked up a virtual, can get (e.g.) final String.hashCode.
        assert (refKind == REF_invokeSpecial) : this;
        return true;
    }
    assert (false) : this + " != " + MethodHandleNatives.refKindName((byte) originalRefKind);
    return true;
  }

  private boolean staticIsConsistent() {
    byte refKind = getReferenceKind();
    return MethodHandleNatives.refKindIsStatic(refKind) == isStatic() || getModifiers() == 0;
  }

  private boolean vminfoIsConsistent() {
    byte refKind = getReferenceKind();
    assert (isResolved());  // else don't call
    Object vminfo = MethodHandleNatives.getMemberVMInfo(this);
    assert (vminfo instanceof Object[]);
    long vmindex = (Long) ((Object[]) vminfo)[0];
    Object vmtarget = ((Object[]) vminfo)[1];
    if (MethodHandleNatives.refKindIsField(refKind)) {
      assert (vmindex >= 0) : vmindex + ":" + this;
      assert (vmtarget instanceof Class);
    } else {
      if (MethodHandleNatives.refKindDoesDispatch(refKind)) {
        assert (vmindex >= 0) : vmindex + ":" + this;
      } else {
        assert (vmindex < 0) : vmindex;
      }
      assert (vmtarget instanceof MemberName) : vmtarget + " in " + this;
    }
    return true;
  }

  private MemberName changeReferenceKind(byte refKind, byte oldKind) {
    assert (getReferenceKind() == oldKind);
    assert (MethodHandleNatives.refKindIsValid(refKind));
    flags += (((int) refKind - oldKind) << MN_REFERENCE_KIND_SHIFT);
    return this;
  }

  private boolean testFlags(int mask, int value) {
    return (flags & mask) == value;
  }

  private boolean testAllFlags(int mask) {
    return testFlags(mask, mask);
  }

  private boolean testAnyFlags(int mask) {
    return !testFlags(mask, 0);
  }

  /**
   * Utility method to query if this member is a method handle invocation (invoke or invokeExact).
   * Also returns true for the non-public MH.invokeBasic.
   */
  public boolean isMethodHandleInvoke() {
    final int bits = MH_INVOKE_MODS & ~Modifier.PUBLIC;
    final int negs = Modifier.STATIC;
    if (testFlags(bits | negs, bits) &&
        clazz == MethodHandle.class) {
      return isMethodHandleInvokeName(name);
    }
    return false;
  }

  public static boolean isMethodHandleInvokeName(String name) {
    switch (name) {
      case "invoke":
      case "invokeExact":
      case "invokeBasic":  // internal sig-poly method
        return true;
      default:
        return false;
    }
  }

  private static final int MH_INVOKE_MODS = Modifier.NATIVE | Modifier.FINAL | Modifier.PUBLIC;

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isStatic() {
    return Modifier.isStatic(flags);
  }

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isPublic() {
    return Modifier.isPublic(flags);
  }

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isPrivate() {
    return Modifier.isPrivate(flags);
  }

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isProtected() {
    return Modifier.isProtected(flags);
  }

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isFinal() {
    return Modifier.isFinal(flags);
  }

  /**
   * Utility method to query whether this member or its defining class is final.
   */
  public boolean canBeStaticallyBound() {
    return Modifier.isFinal(flags | clazz.getModifiers());
  }

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isVolatile() {
    return Modifier.isVolatile(flags);
  }

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isAbstract() {
    return Modifier.isAbstract(flags);
  }

  /**
   * Utility method to query the modifier flags of this member.
   */
  public boolean isNative() {
    return Modifier.isNative(flags);
  }
  // let the rest (native, volatile, transient, etc.) be tested via Modifier.isFoo

  // unofficial modifier flags, used by HotSpot:
  static final int BRIDGE = 0x00000040;
  static final int VARARGS = 0x00000080;
  static final int SYNTHETIC = 0x00001000;
  static final int ANNOTATION = 0x00002000;
  static final int ENUM = 0x00004000;

  /**
   * Utility method to query the modifier flags of this member; returns false if the member is not a
   * method.
   */
  public boolean isBridge() {
    return testAllFlags(IS_METHOD | BRIDGE);
  }

  /**
   * Utility method to query the modifier flags of this member; returns false if the member is not a
   * method.
   */
  public boolean isVarargs() {
    return testAllFlags(VARARGS) && isInvocable();
  }

  /**
   * Utility method to query the modifier flags of this member; returns false if the member is not a
   * method.
   */
  public boolean isSynthetic() {
    return testAllFlags(SYNTHETIC);
  }

  static final String CONSTRUCTOR_NAME = "<init>";  // the ever-popular

  // modifiers exported by the JVM:
  static final int RECOGNIZED_MODIFIERS = 0xFFFF;

  // private flags, not part of RECOGNIZED_MODIFIERS:
  static final int
      IS_METHOD = MN_IS_METHOD,        // method (not constructor)
      IS_CONSTRUCTOR = MN_IS_CONSTRUCTOR,   // constructor
      IS_FIELD = MN_IS_FIELD,         // field
      IS_TYPE = MN_IS_TYPE,          // nested type
      CALLER_SENSITIVE = MN_CALLER_SENSITIVE; // @CallerSensitive annotation detected

  static final int ALL_ACCESS = Modifier.PUBLIC | Modifier.PRIVATE | Modifier.PROTECTED;
  static final int ALL_KINDS = IS_METHOD | IS_CONSTRUCTOR | IS_FIELD | IS_TYPE;
  static final int IS_INVOCABLE = IS_METHOD | IS_CONSTRUCTOR;
  static final int IS_FIELD_OR_METHOD = IS_METHOD | IS_FIELD;
  static final int SEARCH_ALL_SUPERS = MN_SEARCH_SUPERCLASSES | MN_SEARCH_INTERFACES;

  /**
   * Utility method to query whether this member is a method or constructor.
   */
  public boolean isInvocable() {
    return testAnyFlags(IS_INVOCABLE);
  }

  /**
   * Utility method to query whether this member is a method, constructor, or field.
   */
  public boolean isFieldOrMethod() {
    return testAnyFlags(IS_FIELD_OR_METHOD);
  }

  /**
   * Query whether this member is a method.
   */
  public boolean isMethod() {
    return testAllFlags(IS_METHOD);
  }

  /**
   * Query whether this member is a constructor.
   */
  public boolean isConstructor() {
    return testAllFlags(IS_CONSTRUCTOR);
  }

  /**
   * Query whether this member is a field.
   */
  public boolean isField() {
    return testAllFlags(IS_FIELD);
  }

  /**
   * Query whether this member is a type.
   */
  public boolean isType() {
    return testAllFlags(IS_TYPE);
  }

  /**
   * Utility method to query whether this member is neither public, private, nor protected.
   */
  public boolean isPackage() {
    return !testAnyFlags(ALL_ACCESS);
  }

  /**
   * Query whether this member has a CallerSensitive annotation.
   */
  public boolean isCallerSensitive() {
    return testAllFlags(CALLER_SENSITIVE);
  }

  /**
   * Utility method to query whether this member is accessible from a given lookup class.
   */
  public boolean isAccessibleFrom(Class<?> lookupClass) {
    return VerifyAccess
        .isMemberAccessible(this.getDeclaringClass(), this.getDeclaringClass(), flags,
            lookupClass, ALL_ACCESS | MethodHandles.Lookup.PACKAGE);
  }

  /**
   * Initialize a query.   It is not resolved.
   */
  private void init(Class<?> defClass, String name, Object type, int flags) {
    // defining class is allowed to be null (for a naked name/type pair)
    //name.toString();  // null check
    //type.equals(type);  // null check
    // fill in fields:
    this.clazz = defClass;
    this.name = name;
    this.type = type;
    this.flags = flags;
    assert (testAnyFlags(ALL_KINDS));
    assert (this.resolution == null);  // nobody should have touched this yet
    //assert(referenceKindIsConsistent());  // do this after resolution
  }

  /**
   * Calls down to the VM to fill in the fields.  This method is
   * synchronized to avoid racing calls.
   */
  private void expandFromVM() {
    if (type != null) {
      return;
    }
    if (!isResolved()) {
      return;
    }
    MethodHandleNatives.expand(this);
  }

  // Capturing information from the Core Reflection API:
  private static int flagsMods(int flags, int mods, byte refKind) {
    assert ((flags & RECOGNIZED_MODIFIERS) == 0);
    assert ((mods & ~RECOGNIZED_MODIFIERS) == 0);
    assert ((refKind & ~MN_REFERENCE_KIND_MASK) == 0);
    return flags | mods | (refKind << MN_REFERENCE_KIND_SHIFT);
  }

  /**
   * Create a name for the given reflected method.  The resulting name will be in a resolved state.
   */
  public MemberName(Method m) {
    this(m, false);
  }

  @SuppressWarnings("LeakingThisInConstructor")
  public MemberName(Method m, boolean wantSpecial) {
    m.getClass();  // NPE check
    // fill in vmtarget, vmindex while we have m in hand:
    MethodHandleNatives.init(this, m);
    if (clazz == null) {  // MHN.init failed
      if (m.getDeclaringClass() == MethodHandle.class &&
          isMethodHandleInvokeName(m.getName())) {
        // The JVM did not reify this signature-polymorphic instance.
        // Need a special case here.
        // See comments on MethodHandleNatives.linkMethod.
        MethodType type = MethodType.methodType(m.getReturnType(), m.getParameterTypes());
        int flags = flagsMods(IS_METHOD, m.getModifiers(), REF_invokeVirtual);
        init(MethodHandle.class, m.getName(), type, flags);
        if (isMethodHandleInvoke()) {
          return;
        }
      }
      throw new LinkageError(m.toString());
    }
    assert (isResolved() && this.clazz != null);
    this.name = m.getName();
    if (this.type == null) {
      this.type = new Object[]{m.getReturnType(), m.getParameterTypes()};
    }
    if (wantSpecial) {
      if (isAbstract()) {
        throw new AbstractMethodError(this.toString());
      }
      if (getReferenceKind() == REF_invokeVirtual) {
        changeReferenceKind(REF_invokeSpecial, REF_invokeVirtual);
      } else if (getReferenceKind() == REF_invokeInterface)
      // invokeSpecial on a default method
      {
        changeReferenceKind(REF_invokeSpecial, REF_invokeInterface);
      }
    }
  }

  public MemberName asSpecial() {
    switch (getReferenceKind()) {
      case REF_invokeSpecial:
        return this;
      case REF_invokeVirtual:
        return clone().changeReferenceKind(REF_invokeSpecial, REF_invokeVirtual);
      case REF_invokeInterface:
        return clone().changeReferenceKind(REF_invokeSpecial, REF_invokeInterface);
      case REF_newInvokeSpecial:
        return clone().changeReferenceKind(REF_invokeSpecial, REF_newInvokeSpecial);
    }
    throw new IllegalArgumentException(this.toString());
  }

  /**
   * If this MN is not REF_newInvokeSpecial, return a clone with that ref. kind.
   * In that case it must already be REF_invokeSpecial.
   */
  public MemberName asConstructor() {
    switch (getReferenceKind()) {
      case REF_invokeSpecial:
        return clone().changeReferenceKind(REF_newInvokeSpecial, REF_invokeSpecial);
      case REF_newInvokeSpecial:
        return this;
    }
    throw new IllegalArgumentException(this.toString());
  }

  /**
   * If this MN is a REF_invokeSpecial, return a clone with the "normal" kind
   * REF_invokeVirtual; also switch either to REF_invokeInterface if clazz.isInterface.
   * The end result is to get a fully virtualized version of the MN.
   * (Note that resolving in the JVM will sometimes devirtualize, changing
   * REF_invokeVirtual of a final to REF_invokeSpecial, and REF_invokeInterface
   * in some corner cases to either of the previous two; this transform
   * undoes that change under the assumption that it occurred.)
   */
  public MemberName asNormalOriginal() {
    byte normalVirtual = clazz.isInterface() ? REF_invokeInterface : REF_invokeVirtual;
    byte refKind = getReferenceKind();
    byte newRefKind = refKind;
    MemberName result = this;
    switch (refKind) {
      case REF_invokeInterface:
      case REF_invokeVirtual:
      case REF_invokeSpecial:
        newRefKind = normalVirtual;
        break;
    }
    if (newRefKind == refKind) {
      return this;
    }
    result = clone().changeReferenceKind(newRefKind, refKind);
    assert (this.referenceKindIsConsistentWith(result.getReferenceKind()));
    return result;
  }

  /**
   * Create a name for the given reflected constructor.  The resulting name will be in a resolved
   * state.
   */
  @SuppressWarnings("LeakingThisInConstructor")
  public MemberName(Constructor<?> ctor) {
    ctor.getClass();  // NPE check
    // fill in vmtarget, vmindex while we have ctor in hand:
    MethodHandleNatives.init(this, ctor);
    assert (isResolved() && this.clazz != null);
    this.name = CONSTRUCTOR_NAME;
    if (this.type == null) {
      this.type = new Object[]{void.class, ctor.getParameterTypes()};
    }
  }

  /**
   * Create a name for the given reflected field.  The resulting name will be in a resolved state.
   */
  public MemberName(Field fld) {
    this(fld, false);
  }

  @SuppressWarnings("LeakingThisInConstructor")
  public MemberName(Field fld, boolean makeSetter) {
    fld.getClass();  // NPE check
    // fill in vmtarget, vmindex while we have fld in hand:
    MethodHandleNatives.init(this, fld);
    assert (isResolved() && this.clazz != null);
    this.name = fld.getName();
    this.type = fld.getType();
    assert ((REF_putStatic - REF_getStatic) == (REF_putField - REF_getField));
    byte refKind = this.getReferenceKind();
    assert (refKind == (isStatic() ? REF_getStatic : REF_getField));
    if (makeSetter) {
      changeReferenceKind((byte) (refKind + (REF_putStatic - REF_getStatic)), refKind);
    }
  }

  public boolean isGetter() {
    return MethodHandleNatives.refKindIsGetter(getReferenceKind());
  }

  public boolean isSetter() {
    return MethodHandleNatives.refKindIsSetter(getReferenceKind());
  }

  public MemberName asSetter() {
    byte refKind = getReferenceKind();
    assert (MethodHandleNatives.refKindIsGetter(refKind));
    assert ((REF_putStatic - REF_getStatic) == (REF_putField - REF_getField));
    byte setterRefKind = (byte) (refKind + (REF_putField - REF_getField));
    return clone().changeReferenceKind(setterRefKind, refKind);
  }

  /**
   * Create a name for the given class.  The resulting name will be in a resolved state.
   */
  public MemberName(Class<?> type) {
    init(type.getDeclaringClass(), type.getSimpleName(), type,
        flagsMods(IS_TYPE, type.getModifiers(), REF_NONE));
    initResolved(true);
  }

  /**
   * Create a name for a signature-polymorphic invoker.
   * This is a placeholder for a signature-polymorphic instance
   * (of MH.invokeExact, etc.) that the JVM does not reify.
   * See comments on {@link MethodHandleNatives#linkMethod}.
   */
  static MemberName makeMethodHandleInvoke(String name, MethodType type) {
    return makeMethodHandleInvoke(name, type, MH_INVOKE_MODS | SYNTHETIC);
  }

  static MemberName makeMethodHandleInvoke(String name, MethodType type, int mods) {
    MemberName mem = new MemberName(MethodHandle.class, name, type, REF_invokeVirtual);
    mem.flags |= mods;  // it's not resolved, but add these modifiers anyway
    assert (mem.isMethodHandleInvoke()) : mem;
    return mem;
  }

  // bare-bones constructor; the JVM will fill it in
  MemberName() {
  }

  // locally useful cloner
  @Override
  protected MemberName clone() {
    try {
      return (MemberName) super.clone();
    } catch (CloneNotSupportedException ex) {
      throw newInternalError(ex);
    }
  }

  /**
   * Get the definition of this member name.
   * This may be in a super-class of the declaring class of this member.
   */
  public MemberName getDefinition() {
    if (!isResolved()) {
      throw new IllegalStateException("must be resolved: " + this);
    }
    if (isType()) {
      return this;
    }
    MemberName res = this.clone();
    res.clazz = null;
    res.type = null;
    res.name = null;
    res.resolution = res;
    res.expandFromVM();
    assert (res.getName().equals(this.getName()));
    return res;
  }

  @Override
  public int hashCode() {
    return Objects.hash(clazz, getReferenceKind(), name, getType());
  }

  @Override
  public boolean equals(Object that) {
    return (that instanceof MemberName && this.equals((MemberName) that));
  }

  /**
   * Decide if two member names have exactly the same symbolic content.
   * Does not take into account any actual class members, so even if
   * two member names resolve to the same actual member, they may
   * be distinct references.
   */
  public boolean equals(MemberName that) {
    if (this == that) {
      return true;
    }
    if (that == null) {
      return false;
    }
    return this.clazz == that.clazz
        && this.getReferenceKind() == that.getReferenceKind()
        && Objects.equals(this.name, that.name)
        && Objects.equals(this.getType(), that.getType());
  }

  // Construction from symbolic parts, for queries:

  /**
   * Create a field or type name from the given components:
   * Declaring class, name, type, reference kind.
   * The declaring class may be supplied as null if this is to be a bare name and type.
   * The resulting name will in an unresolved state.
   */
  public MemberName(Class<?> defClass, String name, Class<?> type, byte refKind) {
    init(defClass, name, type, flagsMods(IS_FIELD, 0, refKind));
    initResolved(false);
  }

  /**
   * Create a method or constructor name from the given components:
   * Declaring class, name, type, reference kind.
   * It will be a constructor if and only if the name is {@code "&lt;init&gt;"}.
   * The declaring class may be supplied as null if this is to be a bare name and type.
   * The last argument is optional, a boolean which requests REF_invokeSpecial.
   * The resulting name will in an unresolved state.
   */
  public MemberName(Class<?> defClass, String name, MethodType type, byte refKind) {
    int initFlags = (name != null && name.equals(CONSTRUCTOR_NAME) ? IS_CONSTRUCTOR : IS_METHOD);
    init(defClass, name, type, flagsMods(initFlags, 0, refKind));
    initResolved(false);
  }

  /**
   * Create a method, constructor, or field name from the given components:
   * Reference kind, declaring class, name, type.
   */
  public MemberName(byte refKind, Class<?> defClass, String name, Object type) {
    int kindFlags;
    if (MethodHandleNatives.refKindIsField(refKind)) {
      kindFlags = IS_FIELD;
      if (!(type instanceof Class)) {
        throw newIllegalArgumentException("not a field type");
      }
    } else if (MethodHandleNatives.refKindIsMethod(refKind)) {
      kindFlags = IS_METHOD;
      if (!(type instanceof MethodType)) {
        throw newIllegalArgumentException("not a method type");
      }
    } else if (refKind == REF_newInvokeSpecial) {
      kindFlags = IS_CONSTRUCTOR;
      if (!(type instanceof MethodType) ||
          !CONSTRUCTOR_NAME.equals(name)) {
        throw newIllegalArgumentException("not a constructor type or name");
      }
    } else {
      throw newIllegalArgumentException("bad reference kind " + refKind);
    }
    init(defClass, name, type, flagsMods(kindFlags, 0, refKind));
    initResolved(false);
  }

  /**
   * Query whether this member name is resolved to a non-static, non-final method.
   */
  public boolean hasReceiverTypeDispatch() {
    return MethodHandleNatives.refKindDoesDispatch(getReferenceKind());
  }

  /**
   * Query whether this member name is resolved.
   * A resolved member name is one for which the JVM has found
   * a method, constructor, field, or type binding corresponding exactly to the name.
   * (Document?)
   */
  public boolean isResolved() {
    return resolution == null;
  }

  private void initResolved(boolean isResolved) {
    assert (this.resolution == null);  // not initialized yet!
    if (!isResolved) {
      this.resolution = this;
    }
    assert (isResolved() == isResolved);
  }

  void checkForTypeAlias() {
    if (isInvocable()) {
      MethodType type;
      if (this.type instanceof MethodType) {
        type = (MethodType) this.type;
      } else {
        this.type = type = getMethodType();
      }
      if (type.erase() == type) {
        return;
      }
      if (VerifyAccess.isTypeVisible(type, clazz)) {
        return;
      }
      throw new LinkageError("bad method type alias: " + type + " not visible from " + clazz);
    } else {
      Class<?> type;
      if (this.type instanceof Class<?>) {
        type = (Class<?>) this.type;
      } else {
        this.type = type = getFieldType();
      }
      if (VerifyAccess.isTypeVisible(type, clazz)) {
        return;
      }
      throw new LinkageError("bad field type alias: " + type + " not visible from " + clazz);
    }
  }


  /**
   * Produce a string form of this member name.
   * For types, it is simply the type's own string (as reported by {@code toString}).
   * For fields, it is {@code "DeclaringClass.name/type"}.
   * For methods and constructors, it is {@code "DeclaringClass.name(ptype...)rtype"}.
   * If the declaring class is null, the prefix {@code "DeclaringClass."} is omitted.
   * If the member is unresolved, a prefix {@code "*."} is prepended.
   */
  @SuppressWarnings("LocalVariableHidesMemberVariable")
  @Override
  public String toString() {
    if (isType()) {
      return type.toString();  // class java.lang.String
    }
    // else it is a field, method, or constructor
    StringBuilder buf = new StringBuilder();
    if (getDeclaringClass() != null) {
      buf.append(getName(clazz));
      buf.append('.');
    }
    String name = getName();
    buf.append(name == null ? "*" : name);
    Object type = getType();
    if (!isInvocable()) {
      buf.append('/');
      buf.append(type == null ? "*" : getName(type));
    } else {
      buf.append(type == null ? "(*)*" : getName(type));
    }
    byte refKind = getReferenceKind();
    if (refKind != REF_NONE) {
      buf.append('/');
      buf.append(MethodHandleNatives.refKindName(refKind));
    }
    //buf.append("#").append(System.identityHashCode(this));
    return buf.toString();
  }

  private static String getName(Object obj) {
    if (obj instanceof Class<?>) {
      return ((Class<?>) obj).getName();
    }
    return String.valueOf(obj);
  }

  public IllegalAccessException makeAccessException(String message, Object from) {
    message = message + ": " + toString();
    if (from != null) {
      message += ", from " + from;
    }
    return new IllegalAccessException(message);
  }

  private String message() {
    if (isResolved()) {
      return "no access";
    } else if (isConstructor()) {
      return "no such constructor";
    } else if (isMethod()) {
      return "no such method";
    } else {
      return "no such field";
    }
  }

  public ReflectiveOperationException makeAccessException() {
    String message = message() + ": " + toString();
    ReflectiveOperationException ex;
    if (isResolved() || !(resolution instanceof NoSuchMethodError ||
        resolution instanceof NoSuchFieldError)) {
      ex = new IllegalAccessException(message);
    } else if (isConstructor()) {
      ex = new NoSuchMethodException(message);
    } else if (isMethod()) {
      ex = new NoSuchMethodException(message);
    } else {
      ex = new NoSuchFieldException(message);
    }
    if (resolution instanceof Throwable) {
      ex.initCause((Throwable) resolution);
    }
    return ex;
  }

  /**
   * Actually making a query requires an access check.
   */
    /*non-public*/
  static Factory getFactory() {
    return Factory.INSTANCE;
  }

  /**
   * A factory type for resolving member names with the help of the VM.
   * TBD: Define access-safe public constructors for this factory.
   */
    /*non-public*/ static class Factory {

    private Factory() {
    } // singleton pattern

    static Factory INSTANCE = new Factory();

    private static int ALLOWED_FLAGS = ALL_KINDS;

    /// Queries
    List<MemberName> getMembers(Class<?> defc,
        String matchName, Object matchType,
        int matchFlags, Class<?> lookupClass) {
      matchFlags &= ALLOWED_FLAGS;
      String matchSig = null;
      if (matchType != null) {
        matchSig = BytecodeDescriptor.unparse(matchType);
        if (matchSig.startsWith("(")) {
          matchFlags &= ~(ALL_KINDS & ~IS_INVOCABLE);
        } else {
          matchFlags &= ~(ALL_KINDS & ~IS_FIELD);
        }
      }
      final int BUF_MAX = 0x2000;
      int len1 = matchName == null ? 10 : matchType == null ? 4 : 1;
      MemberName[] buf = newMemberBuffer(len1);
      int totalCount = 0;
      ArrayList<MemberName[]> bufs = null;
      int bufCount = 0;
      for (; ; ) {
        bufCount = MethodHandleNatives.getMembers(defc,
            matchName, matchSig, matchFlags,
            lookupClass,
            totalCount, buf);
        if (bufCount <= buf.length) {
          if (bufCount < 0) {
            bufCount = 0;
          }
          totalCount += bufCount;
          break;
        }
        // JVM returned to us with an intentional overflow!
        totalCount += buf.length;
        int excess = bufCount - buf.length;
        if (bufs == null) {
          bufs = new ArrayList<>(1);
        }
        bufs.add(buf);
        int len2 = buf.length;
        len2 = Math.max(len2, excess);
        len2 = Math.max(len2, totalCount / 4);
        buf = newMemberBuffer(Math.min(BUF_MAX, len2));
      }
      ArrayList<MemberName> result = new ArrayList<>(totalCount);
      if (bufs != null) {
        for (MemberName[] buf0 : bufs) {
          Collections.addAll(result, buf0);
        }
      }
      result.addAll(Arrays.asList(buf).subList(0, bufCount));
      // Signature matching is not the same as type matching, since
      // one signature might correspond to several types.
      // So if matchType is a Class or MethodType, refilter the results.
      if (matchType != null && matchType != matchSig) {
        for (Iterator<MemberName> it = result.iterator(); it.hasNext(); ) {
          MemberName m = it.next();
          if (!matchType.equals(m.getType())) {
            it.remove();
          }
        }
      }
      return result;
    }

    /**
     * Produce a resolved version of the given member.
     * Super types are searched (for inherited members) if {@code searchSupers} is true.
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * If lookup fails or access is not permitted, null is returned.
     * Otherwise a fresh copy of the given member is returned, with modifier bits filled in.
     */
    private MemberName resolve(byte refKind, MemberName ref, Class<?> lookupClass) {
      MemberName m = ref.clone();  // JVM will side-effect the ref
      assert (refKind == m.getReferenceKind());
      try {
        m = MethodHandleNatives.resolve(m, lookupClass);
        m.checkForTypeAlias();
        m.resolution = null;
      } catch (LinkageError ex) {
        // JVM reports that the "bytecode behavior" would get an error
        assert (!m.isResolved());
        m.resolution = ex;
        return m;
      }
      assert (m.referenceKindIsConsistent());
      m.initResolved(true);
      assert (m.vminfoIsConsistent());
      return m;
    }

    /**
     * Produce a resolved version of the given member. Super types are searched (for inherited
     * members) if {@code searchSupers} is true. Access checking is performed on behalf of the given
     * {@code lookupClass}. If lookup fails or access is not permitted, a {@linkplain
     * ReflectiveOperationException} is thrown. Otherwise a fresh copy of the given member is
     * returned, with modifier bits filled in.
     */
    public <NoSuchMemberException extends ReflectiveOperationException>
    MemberName resolveOrFail(byte refKind, MemberName m, Class<?> lookupClass,
        Class<NoSuchMemberException> nsmClass)
        throws IllegalAccessException, NoSuchMemberException {
      MemberName result = resolve(refKind, m, lookupClass);
      if (result.isResolved()) {
        return result;
      }
      ReflectiveOperationException ex = result.makeAccessException();
      if (ex instanceof IllegalAccessException) {
        throw (IllegalAccessException) ex;
      }
      throw nsmClass.cast(ex);
    }

    /**
     * Produce a resolved version of the given member.
     * Super types are searched (for inherited members) if {@code searchSupers} is true.
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * If lookup fails or access is not permitted, return null.
     * Otherwise a fresh copy of the given member is returned, with modifier bits filled in.
     */
    public MemberName resolveOrNull(byte refKind, MemberName m, Class<?> lookupClass) {
      MemberName result = resolve(refKind, m, lookupClass);
      if (result.isResolved()) {
        return result;
      }
      return null;
    }

    /**
     * Return a list of all methods defined by the given class.
     * Super types are searched (for inherited members) if {@code searchSupers} is true.
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * Inaccessible members are not added to the last.
     */
    public List<MemberName> getMethods(Class<?> defc, boolean searchSupers,
        Class<?> lookupClass) {
      return getMethods(defc, searchSupers, null, null, lookupClass);
    }

    /**
     * Return a list of matching methods defined by the given class.
     * Super types are searched (for inherited members) if {@code searchSupers} is true.
     * Returned methods will match the name (if not null) and the type (if not null).
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * Inaccessible members are not added to the last.
     */
    public List<MemberName> getMethods(Class<?> defc, boolean searchSupers,
        String name, MethodType type, Class<?> lookupClass) {
      int matchFlags = IS_METHOD | (searchSupers ? SEARCH_ALL_SUPERS : 0);
      return getMembers(defc, name, type, matchFlags, lookupClass);
    }

    /**
     * Return a list of all constructors defined by the given class.
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * Inaccessible members are not added to the last.
     */
    public List<MemberName> getConstructors(Class<?> defc, Class<?> lookupClass) {
      return getMembers(defc, null, null, IS_CONSTRUCTOR, lookupClass);
    }

    /**
     * Return a list of all fields defined by the given class.
     * Super types are searched (for inherited members) if {@code searchSupers} is true.
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * Inaccessible members are not added to the last.
     */
    public List<MemberName> getFields(Class<?> defc, boolean searchSupers,
        Class<?> lookupClass) {
      return getFields(defc, searchSupers, null, null, lookupClass);
    }

    /**
     * Return a list of all fields defined by the given class.
     * Super types are searched (for inherited members) if {@code searchSupers} is true.
     * Returned fields will match the name (if not null) and the type (if not null).
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * Inaccessible members are not added to the last.
     */
    public List<MemberName> getFields(Class<?> defc, boolean searchSupers,
        String name, Class<?> type, Class<?> lookupClass) {
      int matchFlags = IS_FIELD | (searchSupers ? SEARCH_ALL_SUPERS : 0);
      return getMembers(defc, name, type, matchFlags, lookupClass);
    }

    /**
     * Return a list of all nested types defined by the given class.
     * Super types are searched (for inherited members) if {@code searchSupers} is true.
     * Access checking is performed on behalf of the given {@code lookupClass}.
     * Inaccessible members are not added to the last.
     */
    public List<MemberName> getNestedTypes(Class<?> defc, boolean searchSupers,
        Class<?> lookupClass) {
      int matchFlags = IS_TYPE | (searchSupers ? SEARCH_ALL_SUPERS : 0);
      return getMembers(defc, null, null, matchFlags, lookupClass);
    }

    private static MemberName[] newMemberBuffer(int length) {
      MemberName[] buf = new MemberName[length];
      // fill the buffer with dummy structs for the JVM to fill in
      for (int i = 0; i < length; i++) {
        buf[i] = new MemberName();
      }
      return buf;
    }
  }

//    static {
//        System.out.println("Hello world!  My methods are:");
//        System.out.println(Factory.INSTANCE.getMethods(MemberName.class, true, null));
//    }
}
